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Molecular screening of tomato genotypes for resistance to meloidogyne incognita, fusarium oxysporum and ralstonia solanacearum for genetic improvement

Abstract:

Tomato diseases caused by Meloidogyne incognita, Fusarium oxysporum f. sp. lycopersici, and Ralstonia solanacearum are worldwide major concerns because of economic losses due to crop damage or to the cost of the control measures. Resistant varieties development reduces pesticide usage, therefore it is strongly desirable to have morphological, molecular and agronomically characterized germplasm. This research aimed to validate the use of SCAR molecular markers Mi-23F/Mi-23R; At2-F3/At2-R3; I-2/5F/I-2/5R; P7-43DF3/P7-43DR1; P7-43DF1/P7-43DR1; TSCARaatF/R and TSCARaagF/R, associated with Mi-1.2, I-1, I-2, I-3 and TRSR-1 resistance genes, to characterize molecularly 144 materials including Solanum lycopersicum, Solanum lycopersicum var cerasiforme, S. pimpinellifolium, S. neorickii, S. habrochaites, and advanced families derived from crosses of wild genotypes with a local variety for purposes of plant breeding. Using a marker associated to the resistance gene Mi- 1.2 we determined that most of the materials had the band associated with susceptibility to the nematode except for the commercial genotype used as control, presumably with the resistance gene. Most of the assessed accessions had the bands associated to resistance gene I-1, although bands associated to susceptibility, heterozygosis, or resistance towards I-2 and I-3 genes were observed. Studied genotypes showed resistance genes towards R. solanacearum. Molecular markers allowed the screening of genotypes for resistance to three major diseases currently affecting tomato.